In recent years, trucking companies have become more conscious of the costs of fuel consumed by their vehicles, particularly those trucks—which are very often referred to as tractors—whose purpose is to tow a trailer or trailers along the roadway, and especially at high speeds along a highway. While the manufacturers of such trucks are doing their best to improve efficiencies by making their truck designs more aerodynamic, and making their engines more fuel efficient, the fact remains that significant aerodynamic losses occur as a result of trailer design, especially at high speed. The current trailer designs create drag on the trailer due to wind resistance as the trailer moves. Even if the engine and the aerodynamic design of the trucks is improved, there still remains the problem of reducing the drag created by the trailer, so as to thereby increase the fuel efficiency of the towing truck.
Federal and state authorities in the United States and Canada are increasingly tightening the restrictions as they apply to the trucking industry, requiring increased efficiency so as to reduce carbon and greenhouse gas emissions from the trucks. Indeed, the California Air Resources Board has mandated that trailers must manifest lower drag coefficients so as to reduce carbon and greenhouse gas emissions in that state.
One common approach to reduction of drag by trailers has been to fit or retrofit the trailers with fairings mounted along each side of the trailer, as seen in, for example, U.S. Pat. No. 7,578,541.
Another approach has been to provide a central drag reduction plate along at least a portion of the trailer length, as described in U.S. patent publication No. 2013/0285411. The central drag reduction plate can be located adjacent to an additional transverse fairing which extends across the trailer, in front of the rear set of wheels. It is well established that trailer wheel assemblies are not aerodynamic and can increase the drag on the trailer when it is driven.
Other approaches have included the use of a variety of fairing of different sizes and shapes located on the underside of the trailer. These are typically located at or near the landing gear assemblies, and/or the trailer wheel assemblies.
While these approaches do provide some aerodynamic advantages, and thus some fuel economy benefits, further improvement in this area is always desirable.
Further, common in the trucking industry is the use of multiple trailers attached in series to a single tractor. In this approach, a first additional trailer is typically attached to the tractor, or attached to a fifth wheel assembly located at the back of the tractor. At the back of the first trailer is trailer hitching assembly, such as an pintle hook, to which a converter dolly assembly can be attached. The converter dolly assembly comprises a support frame to which a wheel assembly, and an additional fifth wheel assembly is attached, and also includes a corresponding hitching assembly, such as an pintle eye at its front end, which is adapted to be connected to the trailer pintle hook. A further trailer (sometimes referred to as a “pup” trailer) can be attached to the converter dolly, by use of the additional fifth wheel.
In turn, the second trailer can also include a further pintle hook, or other hitching assembly, to which a further converter dolly, and thus trailer, can be fitted.
While use of converter dollies is well established in order to add an additional trailer or trailers to a tractor-trailer or truck-trailer configuration, there has been little attempt to improve the aerodynamics around the dolly, and its integral wheel assembly.
The present inventors have unexpectedly discovered that placing fairings on the dolly, in front of the wheels on each side of the wheel assembly, will reduce drag on the tractor-trailer combination, especially at higher speeds. Regardless of the use of other fairings fitted to the tractor and/or trailer, the fairings of the present invention, attached to the converter dolly, provide additional aerodynamic benefits.